John Greenland
CVRS Member

Hi Rick,

A couple of things about the mod sort of jump out at me.

1: There is no plate resistor on the 27 tube. The signal from the plate of that tube goes basically to ground. The mod was an attempt to create a phase splitter circuit from existing hardware so that the 2 output 45’s would have opposite signals on their control grids. Without a resistor in the plate circuit there will not a signal for one of the 45’s.

2: There is no negative bias applied to the grids of the 45’s. This would have come from point “C” in the original circuit and is a result of the resistor in the ground/common connection of the power transformer being routed thru a resistor. The voltage is probably around 40 volts or so. There also does not appear to be any bias for the 27 tube as well.

Hope this helps.

John G. VO1 CAT